Isomerization of paraffinic hydrocarbons with fused salt complex of aluminum halide and manganous halide deposited on a carrier

ABSTRACT

A catalyst composition for hydrocarbon conversions such as paraffin isomerization is described which comprises a porous, refractory inorganic oxide carrier having deposited thereon a fused salt complex consisting of aluminum chloride and/or bromide and manganous chloride and/or bromide, said fused salt complex being formed by heating a composite mixture of the halide salts to a temperature above the melting point of the composite.

This is a division of application Ser. No. 593,336, filed July 3, 1975,now U.S. Pat. No. 3,992,326.

BACKGROUND OF THE INVENTION

This invention relates to a supported acidic catalyst composition andvarious processes in which the catalyst can be employed to promotehydrocarbon conversion reactions especially useful in petroleumrefining. More particularly, this invention is directed to a catalyticcomposition having superior stability in hydrocarbon conversions such aslow temperature paraffin isomerization and paraffin alkylation, whichcomprises a fused salt complex of certain aluminum halides and manganoushalides present on the surface of a porous, refractory carrier, and toits use in such hydrocarbon conversion processes.

Catalytic hydrocarbon conversion processes such as skeletalisomerization of isomerizable paraffins and cycloparaffins and ethylenealkylation of paraffinic hydrocarbons has long been recognized in theart. In the area of petroleum refining, processes such as paraffinisomerization have more recently acquired greater importance because ofthe need to maintain high octane ratings for motor fuels at the reducedlevels of tetraethyllead or other organolead antiknock agents nowmandated by environmental and legislative constraints. In this regard,isomerization of straight chain or slightly branched C₅ and C₆paraffinic hydrocarbons to more highly branched hydrocarbons such asisopentane and dimethylbutane has been recognized as a viablealternative to the addition of lead compounds to motor fuel as a meansof obtaining such high octane motor fuel.

The use of acidic hydrocarbon conversion catalysts of the Friedal-Craftstype in promoting isomerization and/or alkylation reactions is wellknown. In the case of paraffin or saturated aliphatic hydrocarbonisomerization, metal halides or mixtures of metal halides, e.g.,aluminum chloride, aluminum bromide, zinc chloride, antimony chloride,etc., have generally been employed on a variety of refractory supportsto effect isomerization of C₄ to C₆ hydrocarbons at temperatures ranginganywhere from 150° to 600° F., e.g., see U.S. Pat. Nos. 2,250,410 and3,060,249. In such processes, a hydrogen halide is usually added alongwith the feed to act as a promoter or co-catalyst for the reaction whilea hydrogen partial pressure is also maintained in the reaction zone tosuppress undesired side reactions such as cracking of feed to lowermolecular weight hydrocarbons and to prolong the catalyst life. To aidin suppressing these side reactions, it has been recognized that thecatalyst composition, itself, can be modified via the incoporation of ahydrogenation component, e.g., platinum and platinum group metals, toimpart a hydrogenation-dehydrogenation function along with theFriedal-Crafts activity, e.g., see U.S. Pat. Nos. 2,900,425, 2,924,629and 2,999,074. Despite the numerous prior art disclosures dealing withsuch Friedal-Crafts catalysts, their acceptance on a commercial scalehas not been outstanding in the area of paraffin isomerization. Whilethe reasons for the limited commercial success of such catalyst arevaried, some of the more substantial problems encountered include therequirement of higher reaction temperatures, e.g., 400° F. or above, foradequate catalyst activity and the high rates of catalyst deactivationdue to metal salt losses from the catalyst bulk and side reactionproduct, e.g., cracking, contamination of the catalyst. In the formercase, higher isomerization reaction temperatures are undesirable becausethe formation of highly branched, high octane value-dimethylbutane isfavored by low temperature, e.g., 200° F., operation. In the lattercase, metal salt losses, especially aluminum halides, via volatilizationfrom the catalyst often require that additional halide be added to thereaction zone on a continuous basis and even then the catalyst lifetimesare not of sufficient duration to be attractive on a commercial scale.Accordingly, it would be of advantage if a Friedal-Crafts type catalystcould be developed which has good activity at low temperatures yet isnot subject to deactivation to the extent previously encountered. Inthis respect it would be especially desirable if a catalyst compositionemploying aluminum halides as the acidic hydrocarbon conversioncomponent could be found in which the need to continuously add freshaluminum halide to the reaction zone is minimized or avoided since thisaddition significantly increases the costs and complexity of theprocess.

DESCRIPTION OF THE PRIOR ART

Fused salt compounds or complexes formed by melting an admixture ofmanganous chloride or bromide with aluminum chloride or bromide,respectively, have been reported by Kendall, Crittendan and Miller in J.Am. Chem. Soc., 45, 963 (1923). While no definite compositional formulaof the complexes or compounds was given in that article, thecompositions were assigned a tentative stoichiometry of 2 AlX₃.MnX₂based on molecular proportions (X indicating Cl or Br). In subsequentstudies, complexes or divalent metal halides and aluminum halidesincluding manganous halides have been assigned the tentative compositionof M (AlX₄)₂ (M = metal, X = halide), e.g., see Belt and Scott,Inorganic Chem. 3, No. 12, 1785-1788 (1964) though this compositionalformula has not been completely verified except in the case ofCo(AlCl₄)₂ i.e., see Ibers Acta Cryst. 15, 967 (1962). According to theI.U.P.A.C. and other literature references, such as those describedabove, these compounds or complexes have been named both as substitutedaluminates and as alanates, i.e., tetrahaloaluminates andtetrahaloalantes, respectively.

In the area of catalysis, there is no known teaching which attributesany significant activity specifically to the solid form of the fusedsalt complexes formed from manganous chloride or bromide and aluminumchloride or bromide; nor further, even any disclosure of their existanceas solids on refractory carriers. In this regard, the most relevantprior art appears to be U.S. Pat. No. 2,360,699 which is directed toliquid phase hydrocarbon conversion, e.g., isomerization with a moltensalt mixture containing halides of the Friedal-Crafts type, e.g., AlCl₃,combined with anyone of a large number of other metal halide saltsincluding manganese. However, in that patent teaching the hydrocarbonconversion reactions are carried out in a fluidized bed at a temperatureabove the melting point of the salt mixture such that the catalystremains in the molten form while in contact with the reaction mass.

SUMMARY OF THE INVENTION

It has now been found that the fused salt complexes of certain manganoushalides and certain aluminum halides, i.e., chlorides and/or bromides,when deposited on porous, refractory inorganic oxide carriers providesolid catalytic compositions having high activity in hydrocarbonconversion reactions such as isomerization or alkylation combined withvery low rates of catalyst deactivation due to metal salt loss and sidereaction contamination of catalyst. In fact, it appears that use of theinstant catalysts in processes such as low temperature isomerizationwill afford catalyst lifetimes in excess of one year without employingaluminum halide makeup and scrubbing facilities traditionally associatedwith the use of volatile aluminum halide salts in such processes.

Accordingly, in its broadest aspects, the instant invention provides asolid catalytic composition suitable for use in hydrocarbon conversionreactions which comprises a fused salt complex of an aluminum halideselected from the class consisting of aluminum chloride, aluminumbromide and mixtures thereof and a manganous halide selected from theclass consisting of manganous chloride, manganous bromide and mixturesthereof present on the surfaces of a porous, refractory inorganic oxidecarrier, said solid catalytic composition being formed by heating acomposite mixture of the halide salt components of the fused saltcomplex to a temperature above the melting point of the composite,depositing the melted composite on the carrier surfaces and cooling ofthe carrier containing the melted composite to a temperature below themelting point of the fused salt complex. Also within the scope of theinvention are those hydrocarbon conversion processes, i.e., lowtemperature isomerization of paraffinic hydrocarbons, in which the novelcatalytic compositions according to the invention find particularapplication.

Further, according to the invention, it has also been found that ahydrogenation component such as metals from Group VIII of the PeriodicTable of Elements can be advantageously incorporated into the catalystcomposition of the invention to give it a stability-enhancinghydrogenation function in combination with its acid function.Accordingly, an additional aspect of the instant invention comprises thecatalytic compositions described above wherein the carrier is alsoimpregnated with a metal hydrogenation component.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The catalyst compositions according to the invention are solid,supported acidic hydrocarbon conversion catalysts of the Friedal-Craftstype wherein the acid-acting function is a fused salt complex formed byheating a mixture of aluminum halide and manganous halide to atemperature above the mixture, said metal halide salts being selectedfrom the class consisting of chloride, bromide and mixtures thereof.These catalyst compositions can be prepared by anyone of severaltechniques, it being essential only that the mixture of metal halideforming the fluid salt complex be heated to at least the point offusion, i.e., melting point of the mixture, and deposited on the carrierwhile in this liquid or semi-liquid melted state. One suitable techniqueemployed to prepare catalyst compositions according to the inventioninvolves an initial step to form the fused salt complex by the mixingtogether the metal halide salts in the desired proportions underapplication of heat until a uniform melt is obtained, followed by asubsequent deposition step wherein the carrier is contacted by thepreformed melt in a conventional manner to deposit the desired quantityof fused salt on the carrier surface. In another technique, which ispreferred because of its simplicity and ease of operation, the desiredproportions of each metal halide salt and carrier are combined in aphysical mixture and heated under mixing to at least the fusion point ofthe salt mixture whereby the fused salt complex obtains sufficientfluidity to uniformly impregnate the carrier particles. After depositionof the melted or molten salt complex on the surface of the carrier byeither of the bove techniques, the carrier contaning the molten saltcomplex is subsequently cooled to a temperature at which the melted saltcomplex freezes or becomes solid via any conventional procedure, such asfluidization with a cooling gas, which prevents agglomeration of thecatalyst particles. In either preparation technique, the metal halidesalt starting materials are suitably employed in particulate form, e.g.,powders, granules, etc., of a size convenient for mixing and melting inconventional equipment. To avoid hydrolysis, oxidation and/or otherreactions involving the metal halides, which might otherwise deactivatethe catalyst, e.g., carbon contamination, the catalyst preparation issuitably carried out under anhydrous conditions in a vacuum oratmosphere of hydrogen or inert gas such as nitrogen.

The specific temperature to which the mixture of metal halide salts mustbe heated to obtain the fused salt complex according to the inventionwill depend largely on the particular halide salts employed and theproportions in which the two metal halide salt components are combinedin the metal salt composite. As a general matter, the proportions of thetwo metal halide salts which are suitably combined in a melted compositeto obtain the fused salt complex of the invention range from 3:1 to 1:3manganous halide to aluminum halide, expressed as parts by weight in themelted composite. To fuse or completely melt composite mixtures of thetwo metal salts falling in this general range, it is necessary to employtemperatures in the range of 300° to 1,200° F. with the highertemperatures in the range reflecting increased proportions of themanganous halide salt. For the bromide salts or salt mixtures which arepredominantly bromides (rather than chlorides), the weight ratio ofmanganous halide to aluminum halide preferably ranges from 2:1 to 1:3and the corresponding temperature range required for melting of the saltcomposite suitably ranges from 300° to 800° F.; bromide salts havinglower fusion temperatures than the chloride salts. For the chloridesalts, which are preferred from cost and effectiveness standpoints inthe invention, the weight ratio of manganous chloride to aluminumchloride suitably ranges from 2:1 to 1:2 in the melted composite withtemperatures in the range of 400° to 1000° F being required for fusionof the composite. Most preferably the fused salt complex according tothe invention is made up of manganous chloride and aluminum chloridewhich are melted together in a weight ratio of 1.5:1 to 1:1.5 of MnCl₂:AlCl₃.

The metal halide starting materials for preparation of the fused saltcomplex according to the invention are suitably substantially pure andessentially free of deactivating impurities such as water. These purehalide salts are available from commercial suppliers or, in thealternative, can be prepared from relatively impure materials viaconventional techniques, e.g., sublimation, recrystallization anddrying, etc.

The carrier material employed in the catalytic compositions of thepresent invention is a porous, refractory inorganic oxide. This carrieris suitably of particulate form and may be of any desired shape such asspheres, pills, cakes, extrudates, powders, granules, etc. Preferablythe carrier is porous and adsorptive in nature having a high surfacearea, e.g., 25-500 m² /g. Suitable refractory inorganic oxides includealumina, magnesia, boria, thoria, titanium dioxide, ziroconium dioxide,chromium oxide, zinc oxide, silica-alumina, silica-magnesia,chromia-alumina, alumina-boria, etc. More preferably, the carrier is analumina-containing material having a surface area in the range of150-500 m² /g. Suitable alumina-containing materials are the crystallinealuminas known as the gamma- eta- and theta-aluminas, though thepresence of minor amounts of other well-known refractory oxides such assilica, magnesia, thoria, etc., is not precluded in this preferredclass. Most preferably, the support is a substantially puregamma-alumina having a surface area in the range of 150-300 m² /g. Priorto utilization in the catalyst compositions of the instant invention, itis preferred that the carrier be subject to a treatment such as dryingor calcinattion to assure that it is substantially free of entrainedwater. For alumina-containing carriers it is particularly preferred thatthe carrier be subject to calcination at a temperature of from 800° to1,200° F. for 2 to 24 hours prior to use.

When the catalysts according to the invention are employed in promotingparaffin isomerization, it has been found that catalyst activity can beenhanced, if the catalyst support is chlorided prior to deposition ofthe fused salt complex thereon. This pre-chloriding of the support whichis particularly applicable to the preferred alumina-containing materialsof the invention can be carried out by a variety of techniques. Onemethod which is suitably employed involves impregnating the support withan aqueous solution of hydrochloric acid, ammonium chloride, or metalchloride salt followed by drying at 200° to 300° F. in air for 2 to 24hours and thermal treatment in a hydrogen atmosphere at 500 to 1,000° F.for 2 to 24 hours. Another suitable pre-chloriding technique involvespretreatment with aluminum chloride by mixing the alumina-containingsupport with substantially pure aluminum chloride and then heating to400° to 600° F. in a static system. In any case, it is preferred thatthe pre-chlorided support contain 0.5 to 5% by weight chloride ion basedon support weight.

As indicated previously, it has also been found to be advantageous toincorporate a hydrogenation component into the catalyst compositions ofthe invention. Suitable hydrogenation components include metals fromGroup VIII of the Periodic Table of Elements, with nickel, cobalt andplatinum being preferred. These metal hydrogenation components can beincorporated into the catalyst compositions according to the inventionby any conventional technique and are preferably present only as a minorproportion of the total catalyst composition, e.g., 0.1 to 10% by weightof the finished catalyst. One suitable technique for incorporation ofthe metal hydrogenation component involves impregnation of the supportprior to deposition of the fused halide salt complex with an aqueoussolution of the metal in cationic form, said metal cations being presentin a metal compound selected from the class consisting of oxides,nitrates, acetates and halides. Preferably, the amount of solution usedin this impregnation technique is just sufficient to completely wet thesurface and pores of the support. After impregnation the carrier ispreferably dried at a temperature of from 200° to 300° F. for 2 to 24hours and activated by calcination in a hydrogen atmosphere at atemperature of from 500° to 1,000° F. for 2 to 24 hours. This dried andreduced carrier is then in a suitable form for deposition of the fusedsalt complex according to the procedures described above.

The catalyst compositions prepared as described above are particulatesolids which can be employed directly to promote hydrocarbon conversionreactions such as isomerization and alkylation. The amount of fused saltcomplex employed in the catalyst compositions of the invention can varyquite widely depneding on the particular use sought to be made of thecatalyst. Generally, effective catalyst are obtained when the fusedhalide salt complex makes up about 10 to about 60% by weight of thefinished catalyst (carrier plus fused salt and optional hydrogenationcomponent). For catalysts employing fused salt complexes in which thehalide anion is bromide, it is preferred that the fused salt comprise40-60% by weight of the finished catalyst because of the highermolecular weight of bromide vs. chloride. For the preferred fusedchloride salt complexes of the invention, substantial catalyst activitycan be achieved with catalyst compositions containing about 10 to 50% byweight fused salt complex based on finished catalyst weight, with fusedsalt concentrations in the range of 20 to 40% by weight being mostpreferred.

Throughout this specification the catalyst compositions according to theinvention have been described as being supported fused salt complexes orcompounds of manganous bromide or chloride and aluminum bromide orchloride which are formed by melting together a composite mixture of themetal halides and depositing the melted composite on the surfaces of acarrier. While there is abundant evidence to indicate that the fusedsalt is substantially in the form of a chemically-combined double saltcomplex or compound on the carrier surface, it has not yet been possibleto assign with certainty any definite molecular makeup to the activeform of the fused salt. In view of the prior art teachings (see above),it appears likely that the fused salt is predominantly in the form of atetrahaloaluminate or alanate since aluminum halides and manganoushalides appear to combine chemically in a 2:1 molecular ratio onmelting, at least to the extent the reaction stoichiometry is satisfied.However, it is possible to obtain very stable catalysts which are activein promoting hydrocarbon conversion reactions by combining weight ratiosof the two metal halides which are in substantial variance from theassigned 2:1 molecular ratio. This high catalyst stability which isattributable to both reduced volatility of the aluminum halide andmoderation of the inherent catalytic activity of aluminum halide isindicative of chemical interaction between the two metal halides. In thelatter case, it is postulated that the manganese ions are inserted insome fashion between the aluminum ions in the solid halide structuresince the high stability and moderated activity of the instantcatalysts, as compared to supported aluminum halides, can best beexplained by a spreading out or separation of the active aluminum halidecatalytic sites in the molecular structure of the catalyst. Further, itis known from other prior art teachings that deposition of a metalhalide, such as aluminum chloride, on the surfaces of a carrier havingchemically combined hydroxyl groups, such as the inorganic oxidecarriers of the instant invention, will result in a reaction betweenchloride and hydroxyl groups to yield M-0-AlCl₂ centers wherein M is theinorganic oxide cation e.g. see U.S. Pat. No. 3,705,111. Thus, it ispossible even in cases where the melted salt composite is present in a2:1 AlX₃ :MnX₂ (X = halogen) molecular ratio, that a certain amount ofthe fused salt mass may not exist in the manganous tetrahaloaluminateform previously postulated. Accordingly, for purposes of the instantdescription the term fused salt complex or compound is intended toencompass those mixtures of manganous halide salts and aluminum halidesalts which, on fusion, afford the aforementioned complex-likeproperties, with recognition being given to the fact that thepredominant complex form is very likely a manganous tetrahaloaluminate.

The catalyst compositions of the invention are particularly effective inpromoting the isomerization of less branched paraffinic hydrocarbons tomore branched paraffinic hydrocarbons. In this process application thecatalyst compositions of the invention possess certain advantages overpreviously known supported Friedal-Crafts type catalysts in that theypossess sufficient activity to effectively promote the isomerizationreaction at low temperatures while at the same time exhibiting superiorstability under isomerization reaction conditions. This latterdesireable property is believed to be a primary function of themanganous halide component of the fused salt complex in both reducingthe volatility of the aluminum halide (and consequent salt losses) andsuppressing the cracking activity inherent in the acidic aluminum halidefunction. Extensive cracking of the hydrocarbon feed in theisomerization process is, of course, undesireable because it leads todeposition of carbonaceous material on the catalyst surface andultimately results in catalyst deactivation. In general terms, theisomerization process according to the invention involves conversion ofless branched paraffinic hydrocarbons by contacting said less branchedhydrocarbons e.g., normal paraffin hydrocarbons in the C₄ to C₇ range,in the vapor phase, in the presence of hydrogen and a hydrogen halide,with the supported, fused halide salt complex catalyst of the inventionat a temperature in the range of about 180° to about 250° F. Preferably,the isomerization process according to the invention consists in vaporphase contacting of normal paraffin hydrocarbons of from 5 to 7 carbonatoms with the fused halide salt catalyst compositions of the inventionat a temperature in the range of 180° to 235° F. in the presence ofhydrogen and a hydrogen halide selected from the class consisting ofhydrogen chloride and hydrogen bromide, said hydrogen being present inthe vapor phase at a mole ratio of about 1 to 10 based on thehydrocarbon feed and said hydrogen halide being present in gaseous format a concentration of 1-20% by weight of the total vapor phase.

As a practical matter it is contemplated that the isomerization processaccording to the invention will find its widest application in upgradingthe octane number of light saturate streams utilized in conventionalrefinery operation for gasoline manufacture. This paraffinic hydrocarbonfeedstock will, most preferably, be debutanized and consist principallyof C₅ to C₆ straight chain saturated hydrocarbon i.e. normal pentanesand hexanes. In addition, this preferred feedstock may also containsubstantial amounts of isopentane or 2-methylpentane or mixture thereof,as well as minor quantities of C₆ naphthenic hydrocarbons such asmethylcyclopentane and cyclohexane. Since naphthenic hydrocarbons tendto suppress the isomerization activity of the catalyst, it is preferredthat they comprise no more than about 5% by volume of the hydrocarbonfeedstock and, most preferably, about 0.1 to 2% by volume of the totalhydrocarbon feedstock. Naphthenes, however, can be beneficial formoderating very high activity on start-up or for operating at severeconditions. For isomerization of this C₅ /C₆ paraffinic hydrocarbonfeedstock in the process according to the invention, reaction zonetemperatures in the range of 200° to 230° F. seem to provide the optimumcombination of high catalyst activity and selectivity and long catalystlifetimes. For these reasons, the C₅ /C₆ paraffinic hydrocarbonisomerization is most preferably carried at temperatures in the 200° to230° F. range.

As was noted above, the isomerization process according to the inventionis carried out in the vapor phase in the presence of hydrogen and ahydrogen halide. The hydrogen halide which is suitably hydrogen bromideor hydrogen chloride acts as a promotor or co-catalyst for theisomerization reaction. From cost, availability and effectivenessstandpoints it is preferred to employ hydrogen chloride in thisapplication; however, when metal bromide salts are utilized to make upthe fused salt complex of the invention, it is desirable to employhydrogen bromide as the co-catalyst to avoid replacement of bromide inthe solid catalyst phase with chlorine. However, active catalysts canalso be obtained by using HCl with an Mn Br₂ /AlBr₃ -on-aluminacatalyst. While good isomerization activity can be obtained in theprocess of the invention when the hydrogen halide concentration in thevapor phase in contact with the catalyst is in the preferred range,mentioned above, i.e., 1 - 20% by weight hydrogen halide, it is mostpreferred to employ hydrogen halide concentrations of from about 5 toabout 15% by weight of the total vapor phase. In this manner thecatalyst activity is controlled at a reasonable level for practicaloperation. The presence of free or molecular hydrogen is important insupressing undesired side reactions such as cracking which mightotherwise adversely effect the catalyst life. Since high concentrationsof hydrogen tend to inhibit the isomerization activity of the catalyst,the quantity of hydrogen added to the vapor phase of the catalyticreaction zone should not exceed 10 moles per mole of hydrocarbonreactant feed, said hydrogen preferably being present at a mole ratio ofabout 1 to 10 based on the hydrocarbon feed. Most preferably, thehydrogen is present at a mole ratio of 2.5 to 5 based on hydrocarbonfeed. The hydrogen and hydrogen halide can be added to the vapor phaseof the isomerization reaction zone in any conventional manner; however,they are preferably mixed with the hydrocarbon reactant prior to itsintroduction into the reaction zone to ensure uniform operation.

The isomerization process according to the invention may be conducted inany conventional manner, i.e., batch type or continuous operationemploying the catalyst in a fixed bed, moving bed or fluidized bedsystem. For economic and practical reasons it is preferred to carry outthe process continuously in a fixed catalyst bed system. The apparatusemployed in this preferred operation may be of a conventional naturesuch as a vertical column containing the fixed bed catalyst throughwhich the reacting hydrocarbons are circulated, with an external recycleline to send the reactants back through the bed any number of times. Inthis continuous system, reactant flow rates of from about 0.1 to 2 WHSVbased on total vapor phase mixture throughput may be suitably employed.In any case, the reactant residence time in the reaction zone isdependent to a substantial degree on the severity of the reactionconditions including temperatures, hydrogen halide concentration andhydrogen partial pressure and the particular use sought to be made ofthe process. These factors are well known to one skilled in the art andneed not be further detailed herein.

The reaction zone pressure employed in the isomerization processaccording to the invention is not considered to be critical and may varyover a rather wide range e.g., 200 to 500 psig. In cases where the lowtemperature isomerization of a C₅ /C₆ paraffinic hydrocarbon feedstockhaving the above described composition is carried out, it is preferredto maintain the reaction zone pressure in the range of about 300 toabout 350 psig.

As indicated previously, the catalyst compositions of the inventionexhibit very low rates of catalyst deactivation and superior lifetimeswhen employed for isomerization of paraffinic hydrocarbons. This isparticularly true for the supported catalyst compositions employing afused salt of manganous chloride and aluminum chloride. However, eventhe fused chloride salt catalysts will slowly decline in activity withuse and at some point the activity will no longer be acceptable. As ameans of dealing with this unacceptably low activity, a method has alsobeen developed whereby the deactivated catalyst can be regenerated to anactivity level approximating that of a freshly prepared catalyst. Inbasic terms, this regeneration process involves stripping and crackingof residual hydrocarbons on the catalyst surface with molecular hydrogenand a gaseous mixture of hydrogen chloride and molecular hydrogen athigh temperature followed by high temperature treatment with hydrogenchloride alone. To carry out this regeneration process it is necessaryto first discontinue flow of the isomerization reaction feed over thecatalyst. After reactant flow is stopped the catalyst is then strippedwith a flowing stream of hydrogen for 8 to 24 hours at a temperature inthe range of 180° to 250° F. This initial stripping step removessubstantially all of the volatile hydrocarbon present in the catalyst.Following removal of volatile hydrocarbons, the temperature of thecatalyst is increased to a temperature in the range of 400° to 500° F.and stripped with a gaseous mixture of hydrogen and hydrogen chloride atabout a 0.15:0.25 weight ratio for 8 to 12 hours. This second strippingstep effects cracking and removal of residual hydrocarbons present onthe catalyst. Finally to complete activation of the catalyst, the flowof hydrogen gas is stopped while the flow of hydrogen chloride gas iscontinued for another 4 to 8 hours at the same temperature range. Aftertreatment with hydrogen chloride, the catalyst can be cooled to theisomerization process temperature, e.g., 180°-250° F. and swept with ahydrogen-containing gas for 1 to 4 hours to remove excess hydrogenchloride prior to use in isomerization. Since water may adversely effectthe catalyst, it is preferred that all steps of the regeneration processbe carried out under substantially anhydrous conditions. Aluminum halidemay be added as part of the regeneraation procedure.

Preparation of catalysts according to the invention and their use inhydrocarbon conversion reactions will be further described by thefollowing illustrations which are not to be construed as limiting theinvention.

Illustrative Embodiment I Catalyst Preparation

The catalysts according to the invention were prepared utilizingcommercially obtained gamma-alumina carriers in the 40-80 mesh sizerange which had been calcined at 800° to 1,000° F. for 2 to 4 hours.Representative physical properties for these calcined alumina carriersinclude surface areas of from 190 to 253 m² /g, pore volumes of from0.62 to 0.80 cm³ /g and percent of pore volume in pores over 350 Adiameter ranging from 2.5 to 11.1%. To improve the activity of the finalcatalyst composition the alumina carriers or supports were chlorided byeither of two different techniques. In the first technique employed, thealumina selected was impregnated with an aqueous solution ofhydrochloric acid (3.56% by weight) in a weight ratio of 1.16 partalumina to 1.00 parts HCl solution. This impregnated alumina was thendried for about 17 hours at 250° F. in air and then heated atatmospheric pressure in a flowing stream of hydrogen at 500° for 1 hourand at 900° F. for 2 hours. The final product analysis showed 1.6% byweight Cl. In the second technique, which also functioned to impregnatethe support with a hydrogenation component, the alumina selected wasimpregnated with an aqueous solution of nickel chloride (26% by weight)in a weight ratio of 1.05 part alumina to 1.00 parts solution. Thisimpregnated preparation was then dried and heated under flowing hydrogenaccording to the procedure previously described. The final productanalysis in this case showed 4% by weight Cl.

Three different preparative techniques were utilized to deposit thefused halide salt complex of the invention on the surfaces of thealumina supports obtained, as above. The first of these techniquesinvolved formation of the catalyst in place by melting of the fused saltcomplex starting materials in the presence of the support. The secondtechnique encompassed pre-formation of the complex and subsequentdeposition in melt form on the support. In the third technique, thealumina support was pre-impregnated with an aqueous solution of themanganous halide salt and the complex formed in situ by heating thealuminum halide in the presence of the impregnated support to themelting point of the fused salt complex. These techniques are segregatedfor convenience below under methods A, B and C subheadings.

Method A

The support (alumina) and catalyst salt complex precursors (manganesechloride or bromide and aluminum chloride or bromide) in powder formwere mixed under anhydrous conditions and charged to a tubular reactionzone and heated in place under an initial hydrogen pressure of 350 psigat 450° F. for 1 hour and then at 650° F. for 2 hours. The 650° Ftemperature was sufficient to assure fusion of the metal halide saltprecursors into the fused salt complex of the invention. After heatingat 650° F. for 2 hours, the reactor was cooled to 220° F. and thecatalyst (now in solid form) purged with hydrogen gas for 17 hours atthis temperature. In a second modification of this technique, thereactor temperature was dropped to only 450° F and the catalyst wastreated with an HCl/H₂ stream for 2 hours (reactor pressure of 350 psig)prior to purging with hydrogen at 220° F as described above. Catalystsprepared according to this technique include the following:

    __________________________________________________________________________                     Fused Salt Complex                                           % by wt.                                                                           Aluminum                                                                            Manganous                                                                           Weight Ratio                                                                              % by wt.                                         Cl on                                                                              halide                                                                              halide                                                                              Manganous / Aluminum                                                                      in finished                                      alumina                                                                            Precursor                                                                           Precursor                                                                           halide / halide                                                                           catalyst                                         __________________________________________________________________________    1.7  AlCl.sub.3                                                                          MnCl.sub.2                                                                          1/1         18.4                                             1.6  AlCl.sub.3                                                                          MnCl.sub.2                                                                          1.34/1      28.3                                             1.5  AlCl.sub.3                                                                          MnCl.sub.2                                                                          1/1         31.1                                             4.0  AlCl.sub.3                                                                          MnCl.sub.2                                                                          1/1         18.4                                             0    AlBr.sub.3                                                                          MnBr.sub.3                                                                            1/2.87    52.8                                             __________________________________________________________________________

Method B

Weighed quantities of powdered catalyst salt complex precursors(manganous chloride or bromide and aluminum chloride or bromide) weremixed and heated to gether in a reactor under anhydrous condtions at450° F. for 1 hour and 650° F. for 2 hours. The resulting melt wascooled to ambient temperature and ground to a fine powder underanhydrous conditions. This fine powder was then used in formulatingcatalysts in place of the powdered catalyst precursors in the proceduredescribed under Method A above. Catalysts prepared according to thistechnique include the following:

    __________________________________________________________________________                     Fused Salt Complex                                           % by wt.                                                                           Aluminum                                                                            Manganous                                                                           Weight Ratio                                                                              % by wt.                                         Cl on                                                                              halide                                                                              halide                                                                              Manganous / Aluminum                                                                      in finished                                      Alumina                                                                            Precursor                                                                           Precursor                                                                           halide / halide                                                                           catalyst                                         __________________________________________________________________________    1.7  AlCl.sub.3                                                                          MnCl.sub.2                                                                          1/1         25.3                                             0    AlCl.sub.3                                                                          MnCl.sub.2                                                                          1/2         40                                               __________________________________________________________________________

Method C

The alumina support (0% by wt Cl) was impregnated with an aqueoussolution of MuCl ₂ (61.12g MnCl ₂ /100 ml solution) in a ratio of 68 mlof solution/100g alumina. This impregnated alumina was allowed to stand0.5 hr. at room temperature and then dried at 250° F. for 2 hours.Calcination was at 900° F. for one hour under a stream of nitrogen. Acatalyst was prepared from a portion of this alumina by adding 5.2g ofAlCl₃ to 20g of the alumina containing manganese chloride which aftermixing well was further mixed in a glass-lined autoclave by rotating theautoclave for 2 hours under 25 psig of H₂ at 410° F. The catalystprepared by this technique contained 40% by weight fused salt complexbased on finished catalyst with a weight ratio of 1.1/1 manganesechloride/aluminum chloride in the salt complex.

Illustrative Embodiment II

A catalyst prepared essentially by the procedure described in Method Aof Illustrative Embodiment I was tested for activity in isomerizing atypical C₅ /C₆ paraffinic hydrocarbon feed in a 0.75 inch O.D. tubularmicroreactor. This catalyst, which was prepared in situ in the tubularreactor, consisted of 18.4% by weight MnCl₂ /AlC1₃ salt complex on agamma-alumina support, basis finished catalyst, wherein the metal halidesalt complex was formulated utilizing an MnCl₂ /AlC1₃ weight ratio ofunity. The support also contained 10% by weight Ni and 1.8% by weight Clas a result of being impregnated with an aqueous NiC1₂ solution aspreviously described. Prior to introduction of the isomerizationreaction feed, the catalyst was maintained under a hydrogen atmosphereat the approximate temperature desired for isomerization. To effectisomerization, a mixture of hydrocarbon feed, HCl co-ctalyst and H₂ werepassed over the catalyst in the vapor phase at a start-up temperature of220° F. Other specific start-up conditions included a reactant feed rateof 0.25 WHSV, a reaction zone pressure of 350 psig, an H₂ /hydrocarbon(oil) mole ratio of 10 and 5% by weight concentration of HCl in thefeed. No aluminum chloride was added to the feed during the test.Throughout the test, the reactant composition and other reactionvariables were altered to compensate for variations in catalyst activityand deactivation rates. The results of this test run, including thepertinent reaction variables are summarized in Table I below

                                      Table I                                     __________________________________________________________________________    Time, hrs.                                                                    after start   300 500 950 1700                                                                              1750                                                                              1925                                                                              2075                                                                              2450                                __________________________________________________________________________    Conditions:                                                                    WHSV         0.5 0.5 0.25                                                                              0.25                                                                              0.25                                                                              0.25                                                                              0.25                                                                              0.50                                 H.sub.2 /Oil, molar                                                                        5.0 5.0 4.5 2.8 2.5 1.8 1.8 1.0                                  % HCl in feed                                                                              17.5                                                                              21  21  16  14  14  14  17                                   Pressure, psig                                                                             350 350 350 350 350 250 250 250                                  Temp., ° F                                                                          220 235 235 235 230 230 230 230                                 Feed Composition, %w                                                           Isopentane   5   20  35  35  35  35  35  35                                   n-Pentane    95  80  55  55  55  55  55  55                                   Unidentified 0   0   0   0   0   0   0   0                                    2-Methyl-                                                                     pentane      0   0   0   0   0   0   0   0                                    n-Hexnae     0   0   10  10  10  10  10  10                                    Methylcyclo-                                                                 pentane      0.05                                                                              0   0.05                                                                              0.05                                                                              0.05                                                                              0.05                                                                              0.05                                                                              0                                    Cyclohexane  0   0   0   0   0   0   0   0                                   Product Composition, %w                                                        Cracked      0.08                                                                              0.07                                                                              0.16                                                                              0.17                                                                              0.17                                                                              0.18                                                                              0.20                                                                              0.23                                 Isopentane   66.77                                                                             51.13                                                                             60.47                                                                             66.57                                                                             66.63                                                                             64.70                                                                             64.73                                                                             62.58                                n-Pentane    32.89                                                                             48.58                                                                             27.38                                                                             22.56                                                                             22.18                                                                             24.18                                                                             23.53                                                                             27.60                                2,2-Dimethyl-                                                                 butane       Trace                                                                             Trace                                                                             4.12                                                                              4.26                                                                              4.45                                                                              4.32                                                                              4.57                                                                              3.71                                 2,3-Dimethyl-                                                                 butane       "   "   1.25                                                                              1.15                                                                              1.11                                                                              1.11                                                                              1.17                                                                              1.07                                 2-Methyl-                                                                     pentane      "   "   3.50                                                                              2.91                                                                              2.99                                                                              3.01                                                                              3.13                                                                              2.70                                 3-Methyl-                                                                     pentane      "   "   1.83                                                                              1.51                                                                              1.56                                                                              1.58                                                                              1.64                                                                              1.37                                 n-Hexane     "   "   1.10                                                                              0.84                                                                              0.87                                                                              0.88                                                                              0.91                                                                              0.90                                 Methylcyclo-                                                                  pentane      "   "   0.02                                                                              0.01                                                                              0.02                                                                              0.02                                                                              0.02                                                                              0                                    Cyclohexane  "   "   0.02                                                                              0.02                                                                              0.02                                                                              0.02                                                                              0.02                                                                              0                                   % i-C.sub.5 in C.sub.5                                                                      56.7                                                                              51.28                                                                             68.8                                                                              74.7                                                                              75.0                                                                              72.8                                                                              73.3                                                                              69.4                                % DMB's in C.sub.6 H.sub.14                                                                 --  --  45.5                                                                              50.3                                                                              50.7                                                                              49.8                                                                              50.3                                                                              49.8                                % MCP in C.sub.6 H.sub.12                                                                   --  --  42.2                                                                              39.5                                                                              40.4                                                                              42.4                                                                              41.5                                                                              --                                  AlCl.sub.3 loss, ppmw,                                                        based on product                                                                            22  15  5   3   3   3   3   2                                   __________________________________________________________________________

On the basis of catalyst activity decline rates and AlCl₃ lossesdemonstrated in the above table, it appears that catalyst lifetimes ofat least one year can be achieved with the catalysts of the instantinvention in the absence of aluminum chloride make-up and scrubbingfacilities.

Illustrative Embodiment III

The regeneration of catalyst paraffin isomerization activity wasdemonstrated for a catalyst according to the invention which haddeclined in activity after extended use in isomerization according tothe general procedure described in Illustrative Embodiment II. Thecatalyst employed in this test was similar to that used in IllustrativeEmbodiment II -- i.e., 18.4% by weight MnCl₂ /AlC1₃ on alumina basisfinished catalyst, at an MnCl₂ /A1C1₃ weight ratio of unity -- exceptthe alumina support was chlorided (1.6% by weight Cl) with hydrochloricacid rather than NiC1₂. In this case, the isomerization start-upconditions were 220° F., 350 psig, 10.5 H₂ /hydrocarbon (oil) moleratio, 0.5 WHSV and 3.6% by weight HC1, basis feed. After 2,000 hoursrun time at increasingly rigorous reaction conditions, the catalystactivity for isomerization had declined to a sufficient degree thatregeneration was considered desirable. At this point, the isomerizationreactant feed over the catalyst was discontinued and the followingstepwise regeneration procedure was effected. Firstly, the catalyst wasstripped for 18 hours at 220° F. with H₂ at 0.8 SCF/hour to removevolatile hydrocarbons. Next the temperature of the catalyst was raisedto 450° F. and the catalyst was stripped for 10 hours with H₂ at0.1-0.15 SCF/hour and HCl at 1.3 g/hour. At this point the H₂ -gas stripwas discontinued and stripping HCl was further carried out for anadditional 4.5 hours at the same conditions. Finally, the temperature ofthe catalyst was reduced to 220° F. and the catalyst was swept with H₂at 0.2 SCF/hour for 4 hours. The results of this test run, including thepertinent reaction variables before and after regeneration are recordedin Table II, below.

                                      Table II                                    __________________________________________________________________________    Time, Hrs.    Prior to Regeneration                                                                     After Regeneration                                  After Start   300 1900                                                                              2000                                                                              2001                                                                              2002                                                                              2020                                                                              2190                                                                              2486                                __________________________________________________________________________    Conditions:                                                                    WHSV         0.46                                                                              0.4 0.4 0.4 0.4 0.4 0.4 0.4                                  H.sub.2 /Oil, Molar                                                                        5.3 2.2 2.3 2   1.85                                                                              4.0 4.0 4.0                                  %w HCl in feed                                                                             6   11  10  10  10  9   10  10                                   Pressure, psig                                                                             350 350 350 350 350 350 350 350                                  Temp., ° F                                                                          220 220 220 220 220 220 220 220                                 Feed Composition,%w                                                            Isopentane   33.53                                                                             31.67                                                                             33.29                                                                             33.29                                                                             33.29                                                                             33.29                                                                             31.73                                                                             33.60                                n-Pentane    53.76                                                                             53.56                                                                             52.00                                                                             52.00                                                                             52.00                                                                             52.00                                                                             52.03                                                                             51.54                                Unidentified 0.14                                                                              0.24                                                                              0.24                                                                              0.24                                                                              0.24                                                                              0.24                                                                              0.26                                                                              0.24                                 2-Methylpentane                                                                            1.68                                                                              10.63                                                                             10.84                                                                             10.84                                                                             10.84                                                                             10.84                                                                             12.02                                                                             11.03                                n-Hexane     9.60                                                                              0   0   0   0   0   0   0                                    Methylcyclo-                                                                  pentane      0.53                                                                              1.56                                                                              1.14                                                                              1.14                                                                              1.14                                                                              1.14                                                                              1.58                                                                              1.43                                 Cyclohexane  0.75                                                                              2.34                                                                              2.49                                                                              2.49                                                                              2.49                                                                              2.49                                                                              2.38                                                                              2.15                                Product Composition,%w                                                         Cracked      0.07                                                                              0.13                                                                              0.09                                                                              0.34                                                                              0.36                                                                              0.07                                                                              0.05                                                                              0.04                                 Isopentane   53.43                                                                             48.66                                                                             46.97                                                                             67.82                                                                             67.03                                                                             47.64                                                                             43.87                                                                             42.98                                n-Pentane    34.13                                                                             37.11                                                                             38.04                                                                             20.70                                                                             21.14                                                                             38.18                                                                             41.90                                                                             42.76                                2,2-Dimethyl-                                                                 butane       3.49                                                                              2.90                                                                              2.90                                                                              4.08                                                                              4.12                                                                              2.97                                                                              2.29                                                                              2.05                                 2,3-Dimethyl-                                                                 butane       1.24                                                                              1.34                                                                              1.48                                                                              1.07                                                                              0.92                                                                              1.20                                                                              1.31                                                                              1.54                                 2-Methylpentane                                                                            3.69                                                                              3.54                                                                              3.90                                                                              2.44                                                                              2.51                                                                              3.63                                                                              4.02                                                                              4.16                                 3-Methylpentane                                                                            1.84                                                                              1.84                                                                              2.06                                                                              1.28                                                                              1.29                                                                              1.88                                                                              2.12                                                                              2.19                                 n-Hexane     1.18                                                                              1.04                                                                              1.15                                                                              0.67                                                                              0.67                                                                              1.07                                                                              1.10                                                                              1.05                                 Methylcyclo-                                                                  pentane      0.41                                                                              1.37                                                                              1.36                                                                              0.66                                                                              0.73                                                                              1.26                                                                              1.27                                                                              1.29                                 Cyclohexane  0.62                                                                              2.07                                                                              2.05                                                                              0.94                                                                              1.03                                                                              1.89                                                                              1.86                                                                              1.94                                 Unidentified --  --  --  --  0.20                                                                              0.21                                                                              0.21                                                                              ---% i-C.sub.5                                                                    61.0 56.72 55.25 71.07 76.02                                                  955.5 51.51 50.11               % DMB's in C.sub.6 H.sub.14                                                                 41.7                                                                              39.77                                                                             38.13                                                                             53.96                                                                             53.75                                                                             39.87                                                                             34.50                                                                             32.62                               % n-Hexane in                                                                  C.sub.6 H.sub.14                                                                           10.4                                                                              9.76                                                                              10.03                                                                             6.97                                                                              7.08                                                                              9.78                                                                              9.93                                                                              9.56                                % MCP in C.sub.6 H.sub.12                                                                   39.8                                                                              39.16                                                                             39.77                                                                             41.16                                                                             41.40                                                                             39.98                                                                             40.64                                                                             39.90                               % of Equilibrium Value                                                         i-C.sub.5 in C.sub.5                                                                       74.5                                                                              69.3                                                                              67.5                                                                              86.8                                                                              92.8                                                                              67.8                                                                              62.9                                                                              61.2                                 DMB's in C.sub.6 H.sub.14                                                                  78.1                                                                              74.5                                                                              71.4                                                                              100 100 74.7                                                                              64.6                                                                              61.1                                __________________________________________________________________________

The results given in Table II indicate that substantial regeneration ofcatalysts according to the invention is attainable. The bottom two linesof the table show the percent of equilibrium value for isopentane in thepentanes and for dimethylbutanes in C₆ paraffins at 220° F. After1,900-2,000 hours, 2.2 H₂ /oil molar ratio and 10% by weight HCl in thefeed gave only about a 72% approach to equilibrium. However, immediatelyafter regeneration and under the same operation conditions, theconversion went to equilibrium. Reducing the severity of the reactionconditions by increasing the H₂ /oil ratio from 2.2 to 4.0 resulted inthe same conversion as obtained under more severe conditions just beforeregeneration. The sustained activity of the regenerated catalyst isillustrated in the 466 hour operating period following regenerationduring which the catalyst activity decline was only 0.24% i-C₅ /day.

Illustrative Embodiment IV

A fused bromide salt complex catalyst on a gamma-alumina support wasprepared according to the procedure described in Method A ofIllustrative Embodiment I and tested for isomerization activityutilizing the method described generally in Illustrative Embodiment II.In this test, the alumina support (40-80 mesh) was not pre-chloridedprior to deposition of the fused salt complex and the finished catalystcontained 52.8% by weight of a MnBr₂ /AlBr₃ complex formed by combiningMnBr₂ and AlBr₃ in a MnBr₂ /AlBr₃ weight ratio of 1/2.87. The start-upcondtions for the test included a reaction temperature of 220° F., areactant feed rate of 0.29 WHSV, a reaction zone pressure of 350 psig, aH₂ to hydrocarbon (oil) mole ratio of 8.7 and 5.0% by weight HBr in thefeed. The results of this test run, including the pertinent reactionvariables are given in Table III, below.

                  Table III                                                       ______________________________________                                        Time, hrs.                                                                    after start      1.75    18      19.25 24.5                                   ______________________________________                                        Conditions:                                                                    Hydrocarbon feed,                                                             g/hr            10.0    10.0    10.0  10.0                                    WHSV            0.29    0.29    0.29  0.29                                    H.sub.2 /Oil, Molar                                                                           8.7     7.0     5.8   4.4                                     %w HBr in feed  5.0.sup.a)                                                                            5.0.sup.a)                                                                            5.0.sup.a)                                                                          5.0.sup.a)                              Pressure, psig  350     350     350   350                                     Temp., ° F                                                                             220     220     220   220                                    Feed Composition,%w                                                            Isopentane      34.47   34.47   34.47 34.47                                   n-Pentane       54.36   54.36   54.36 54.36                                   Unidentified    0.13    0.13    0.13  0.13                                    2-Methylpentane 1.72    1.72    1.72  1.72                                    n-Hexane        9.32    9.32    9.32  9.32                                   Product Composition,%w                                                         Cracked         0.01    0.10    0.10  0.12                                    Isopentane      34.80   47.59   50.79 51.44                                   n-Pentane       50.02   43.63   41.90 39.78                                   2,2-Dimethylbutane                                                                            0.29    0.74    0.76  1.48                                    2,3-Dimethylbutane                                                                            0.51    0.87    0.71  0.88                                    2-Methylpentane 4.02    2.95    2.49  3.08                                    3-Methylpentane 1.76    1.42    1.24  1.45                                    n-Hexane        8.59    2.70    2.01  1.77                                   % i-C.sub.5 in C.sub.5                                                                         41.0    52.17   54.79 56.40                                  % DMB's in C.sub.6 H.sub.14                                                                    5.9     18.53   20.45 27.27                                  ______________________________________                                          .sup.a) The 5.0%w HBr in the hydrocarbon feed corresponds on a molar         basis to 2.25%w HCl.                                                     

Illustrative Embodiment V

The activity of the supported fused salt complex catalysts of theinvention in promoting alkylation of isobutane with ethylene wasdemonstrated using the tubular microreactor and catalyst described inIllustrative Embodiment I. In this test, vapor phase alkylation waseffected by passing a gaseous mixture containing isobutane/ethylene at17/1 mole ratio at a space velocity of 1.8 WHSV basis total hydrocarbonover the catalyst at 350 psig and 150° F. Also present in the vapor feedto alkylation were H₂ at an H₂ /total hydrocarbon molar ratio of 2.3 andHCl at a concentration of 1.2% by weight basis total hydrocarbon. Thesereaction conditions were maintained for the first 23 hours of the testrun after which time the HCl concentration was increased to 3.0% byweight basis total hydrocarbon to increase the conversion of ethylene.The results of this test run including data taken at 2 hours after theincrease in HCl concentration are given in Table IV below

                  Table IV                                                        ______________________________________                                        Hours           Percent of Product                                            after Ethylene  2,3-Dimethyl-                                                                            Ethyl  Total Total                                 Start Conversion                                                                              butane     Chloride                                                                             C.sub.6                                                                             C.sub.5 /C.sub.7                      ______________________________________                                        3     100       5          9      36    55                                    7     97        20         12     49    39                                    10    94        28         14     54    32                                    23    72        55         27     66    7                                     25    89        47         32     62    6                                     ______________________________________                                    

From the results given in the table, it is apparent that the catalysttested possesses significant activity for alkyaltion of isobutane to thedesired high octane value, 2,3-dimethylbutane. This alkylation activityappears to increase and/or become more selective as the catalyst ageswith a concomitant reduction in the formation of C₅ and C₇ hydrocarbons.It is thought that the C₅ /C₇ hydrocarbon formation is due topolymerization or oligomerization of ethylene over the catalyst andconsequent cracking of the polymers or oligomers formed.

What is claimed is:
 1. A process for the isomerization of less-branchedparaffinic hydrocarbons to more-branched paraffinic hydrocarbons whichcomprises contacting said less-branched paraffinic hydrocarbons in thevapor phase at a reaction temperature of from about 180° to about 250° Fin the presence of hydrogen and a hydrogen halide with a solid catalyticcomposition comprising a fused salt complex of an aluminum halideselected from the class consisting of aluminum chloride, aluminumbromide and mixtures thereof and a manganous halide selected from theclass consisting of manganous chloride, manganous bromide and mixturesthereof; present on the surfaces of a porous, refractory inorganic oxidecarrier; said solid catalytic composition being formed by heating acomposite mixture of the halide salt components of the fused saltcomplex to a temperature above the melting point of the composite,depositing the melted composite on the carrier surfaces and cooling ofthe carrier containing the melted composite to a temperature below themelting point of the fused salt complex.
 2. The process according toclaim 1 wherein the fused salt complex consists of 1-3 parts by weightof the aluminum halide and 3-1 parts by weight of the manganous halide.3. The process according to claim 2 wherein the aluminum halide isaluminum chloride, the manganous halide is manganous chloride and thehydrogen halide is hydrogen chloride.
 4. The process according to claim2 wherein the aluminum halide is aluminum bromide, the manganous halideis manganous bromide and the hydrogen halide is hydrogen bromide.
 5. Theprocess according to claim 2 wherein the fused salt complex consists of1-1.5 parts by weight of the aluminum halide and 1.5-1 parts by weightof the manganous halide.
 6. The process according to claim 2 wherein thecarrier is an alumina-containing material having a surface area in therange of 150-500 m² /g.
 7. The process according to claim 6 wherein thecarrier is prechlorided such that it contains 0.5 to 5% by weightchloride ion based on carrier weight.
 8. The process according to claim7 wherein the aluminum halide is aluminum chloride and the manganoushalide is manganous chloride.
 9. The process according to claim 2wherein the fused salt complex makes up about 10 to about 60% by weightof the finished catalyst.
 10. The process according to claim 3 whereinthe fused salt complex makes up about 10 to about 50% by weight of thefinished catalyst.
 11. The process according to claim 4 wherein thefused salt complex makes up about 40 to about 60% by weight of thefinished catalyst.
 12. The process according to claim 8 wherein thecarrier is a gamma alumina having a surface area in the range of 150-300m² /g.
 13. The process according to claim 2 wherein a metalhydrogenation function selected from metals in Group VIII of thePeriodic table of elements is incorporated into said catalystcomposition.
 14. The process according to claim 13 wherein the metalhydrogenation function is present in the catalyst composition in aquantity ranging from about 0.1 to 10% by weight of the finishedcatalyst.
 15. The process according to claim 14 wherein the metalhydrogenation function is selected from the class consisting of nickel,cobalt and platinum.
 16. The process according to claim 2 wherein theless-branched paraffinic hydrocarbons are normal paraffin hydrocarbonsin the C₄ to C₇ carbon number range.
 17. The process according to claim16 wherein the reaction temperature is in the range of 180° to 235° F.18. The process according to claim 17 wherein hydrogen is present insaid vapor phase at a mole ratio of about 1 to 10 based on thehydrocarbon feed and the hydrogen halide is selected from the classconsisting of hydrogen chloride and hydrogen bromide, said hydrogenhalide being present in gaseous form at a concentration of 1 to 20% byweight of the total vapor phase.
 19. The process according to claim 18wherein the less-branched paraffinic hydrocarbons consist principally ofC₅ and C₆ straight-chain saturated hydrocarbons with lesser amounts ofiospentane, 2-methylpentane or mixtures thereof and minor quantities ofC₆ naphthenic hydrocarbons also included in said contacting.
 20. Theprocess according to claim 19 wherein said C₆ naphthenic hydrocarbonscomprise no more than about 5% by volume of said less-branchedparaffinic hydrocarbons.
 21. The process according to claim 20 whereinthe reaction temperature is in the range of 200° to 230° F.
 22. Theprocess according to claim 21 wherein the carrier is analumina-containing material having a surface area in the range of 150 to500 m² /g.
 23. The process according to claim 22 wherein the carrier isprechlorided such that it contains 0.5 to 5% by weight chloride ionbased on carrier weight.
 24. The process according to the claim 16wherein the reaction pressure ranges from about 200 to about 500 psig.25. The process according to claim 21 wherein the reaction pressureranges from about 300 to about 350 psig.